PROJECT SUMMARY/ABSTRACT Traumatic brain injury (TBI) is the leading cause of death and acquired disability in children. Data shar- ing is important to maximize the actionable knowledge generated from research data. Sharing TBI data is a goal of the NIH. To achieve that goal, NIH and the U.S. Department of Defense have developed the Federal Interagency TBI Research (FITBIR) Informatics System to serve as a central repository for TBI data. However, FITBIR currently contains little information about children who require critical care after TBI. This proposal will signi?cantly expand the data available in FITBIR about critically in- jured children with TBI. The NICHD-supported PEDiatric vAlidation oF vAriableS in TBI (PEDALFAST) prospective cohort study enrolled 395 consecutive children with acute TBI admitted to the intensive care unit (ICU) at two large level 1 pediatric trauma centers in the U.S. PEDALFAST was the ?rst study to report the use of an important new outcome measure, the Functional Status Scale (FSS), in chil- dren with TBI. PEDALFAST collected information about patient, injury, and imaging characteristics and events from the pre-hospital, Emergency Department (ED), ICU, and rehabilitation phases of care. Aim 1 is to harmonize the PEDALFAST data to the TBI common data elements (CDEs) developed by NIH, develop complete metadata, and deposit the de-identi?ed data and metadata in FITBIR. Aim 2 is to de- velop and distribute a free, open source R data package containing the de-identi?ed, CDE-harmonized PEDALFAST data and metadata. This aim will leverage the structure, metadata, and documentation built into ?packages? in the R statistical programming environment to provide an easy-to-use and well- documented source for the CDE-harmonized PEDALFAST data. This proposal is signi?cant because it will substantially increase the amount of data about critically injured children with TBI available for sec- ondary use. The data will be harmonized to the current gold standard CDEs for pediatric TBI and will be accompanied by complete metadata. This proposal is innovative because the PEDALFAST data will be made available in the largest U.S. TBI data repository (FITBIR) and also as a free and downloadable R data package. This innovative use of an open-source package format will make the data immediately available for reuse by analytic teams. Ready reuse of the PEDALFAST data is anticipated because it will be available in two different well-documented formats.